System and method for powering on-road electric vehicles via wireless power transfer

ABSTRACT

A system for wireless power transfer of on-road vehicles is provided herein. The system includes a plurality of base stations; a power transmission line located beneath a surface of a road having a plurality of segments, each segment having at least one pair of coils and at least one capacitor electrically connected via a switch to the coils in the segment; and at least one vehicle having at least one power receiving segment having at least two coils, connected to at least one capacitor, wherein the at least one vehicle further includes a communication transmitter configured to transmit a power requesting signal, wherein the coils of the power transmitting segment are configured to receive the power requesting signal; and wherein each of the base stations is further configured to feed a plurality of the power transmitting segments with current at a resonance frequency, responsive to the power requesting signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. patentapplication Ser. No. 16/655,395, now U.S. Pat. No. 11,318,845, which wasfiled on Oct. 17, 2019 as a Continuation application of U.S. patentapplication Ser. No. 15/198,844, now U.S. Pat. No. 10,449,865, which wasfiled on Jun. 30, 2016 as a Continuation-in-Part application of PCTPatent Application Number PCT/IL2014/051140, which was filed on Dec. 31,2014 and claims priority from GB Patent Application No. GB1323160.0,filed on Dec. 31, 2013, all of which are incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to systems and methods ofwireless power transfer, and in particular to such methods and systemthat power moving on-road vehicles.

BACKGROUND OF THE INVENTION

Prior to a short discussion of the related art being set forth, it maybe helpful to set forth definitions of certain terms that will be usedhereinafter.

The term “wireless power transfer” (WPT) (also known aspower-over-the-air) refers herein to the transmission of electricalenergy from a power source to an electrical, such as an electrical powergrid or a consuming device, without the use of conductors. In wirelesspower transfer, a wireless transmitter connected to a power sourceconveys the field energy across an intervening space to one or morereceivers, where it is converted back to an electrical current and thenused. Wireless transmission is useful to power electrical devices incases where interconnecting wires are inconvenient, hazardous, or arenot possible. Wireless power techniques fall into two categories,non-radiative and radiative. In non-radiative techniques, power istypically transferred by magnetic fields using magnetic inductivecoupling between coils of wire. Applications of this type includeinductive powering of electric vehicles like trains or buses.

The term “power transmitter” refers herein to the infrastructure side ofa WPT network. In inductory based WPT, the power transmitter includesthe inductance circuitry. The term “power receiver” refers herein to thevehicle side of a WPT network.

The term “non-tracked vehicle” refers herein to on road vehicles thatare not bound to moving along specific tracks, such as cars and buses,as opposed to ordinary and light trains.

Powering non-tracked vehicles over the air pose many challenges. Since anon-tracked vehicle can move lateral to the direction of advancement,there is a danger of the inductance circuits on the power transmitterside (road) and the inductance circuits on the power receiver side(vehicle) become non-overlapping and thus the WPT process becomesinefficient.

Another challenge is to deal with potential radiation hazards due to thecoils positioned right under the road. Yet another challenge is toregulate the current supplied by the network to the vehicle despite avarying load. Unregulated current at the power receiver (vehicle) maylead to unlimited current and destruction of the power receivercircuits. It is also important to provide an efficient yet simplemechanism by which the power receiver (vehicle) requests energy from thepower transmitter (road).

SUMMARY OF THE INVENTION

According to some embodiment of the present invention, a system forwirelessly powering on-road vehicles is provided herein. The system mayinclude: a plurality of base stations configured to output analternating current at a specified frequency; a power line locatedbeneath a surface of a road and comprising a plurality of independentlyswitched power transmitting segments each comprising at least one pairof coils connected electrically in series to at least one capacitorelectrically and via a switch to one of the base stations, forming aswitched power transmission inductance circuitry; and at least onevehicle having at least one power receiving segment having at least twocoils and at least one capacitor forming a power receiving inductancecircuitry, wherein the at least one vehicle further comprises acommunication transmitter configured to transmit a power requestingsignal, wherein the coils of the power transmitting segment areconfigured to receive said power requesting signal, wherein the basestation associated with the coils of the power transmitting segmentreceiving said power requesting signal is further configured to feedsaid power transmitting segment with the alternating current at thespecified frequency being a resonance frequency of said powertransmission and receiving inductance circuitries, responsive to thepower requesting signal.

According to some embodiments of the present invention, the coils ofeach pair of coils at the power transmitting segment are operating inopposite phases.

According to some embodiments of the present invention, the powerrequest signal sent by the vehicle may include only detected wheneverthere is at least a partial overlap between the coils of the powertransmit segment and the coils at the power receive segment.

According to some embodiments of the present invention, the powerrequest signal may include detected by a current loop at a switch cardassociated with the base station, wherein upon detection of a current atthe current loop, and subject to authorization by the base station, thebases station feeds the coils at the power transmitting segment.

According to some embodiments of the present invention, the powerrequest signal may include configured to generate an alternating currentat the current loop, and wherein the detection may include carried outby phase detection.

According to some embodiments of the present invention, the resonancefrequency may be approximately 80 kHz to 100 kHz, and the power requestsignal may be at a frequency of approximately 400 kHz to 1000 khz.

According to some embodiments of the present invention, the vehicle mayinclude auxiliary power receiving segments on both sides of the powerreceiving segment.

According to some embodiments of the present invention, the auxiliarypower receiving segments may include oval or rectangular coils.

According to some embodiments of the present invention, the vehiclefurther may include an electrical motor and an impendence matchingcircuitry configured to receive the current from the power receivinginductance circuitry and deliver an impedance-matched current to theelectrical motor.

According to some embodiments of the present invention, the vehicle mayinclude a super capacitor wherein the impendence matching circuitrydelivers the impedance-matched current to an electrical motor via thesuper capacitor.

According to some embodiments of the present invention, the vehicle mayinclude a voltage regulator that prevents an output voltage at theelectrical motor from exceeding a predefined value.

According to some embodiments of the present invention, the voltageregulator may include a circuit that senses a reference voltage over apredefined value and repeatedly discharges at least one capacitor untilthe reference voltage goes under the predefined value.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which likereference numerals indicate corresponding, analogous or similarelements, and in which:

FIGS. 1A, 1B and 1C are schematic top view illustration and frontalcross-sectional view illustrations, respectively, of a system forpowering an electric vehicle according to some embodiments of thepresent invention;

FIGS. 2A and 2B are cross-sectional schematic illustrations of anair-core transformer according to some embodiments of the presentinvention;

FIGS. 3A and 3B are side and beneath views of multi-phase receiver unitsin receiver arrays according to some embodiments of the presentinvention;

FIG. 4 is a schematic illustration of side, top and beneath view of amulti-phase power transmission line, according to some embodiments ofthe present invention;

FIG. 5 is a schematic cross-sectional illustration of an accumulatorsystem according to some embodiments of the present invention;

FIGS. 6A-6D are schematic illustrations of electrical arrangements of athree-coil section and of a six-coil section, respectively, according tosome embodiments of the present invention;

FIG. 7 is an underneath view schematic illustration of a single-phasereceiver and a single-phase accumulator according to some embodiments ofthe present invention, which may replace the receiver and accumulator insome embodiments of the present invention;

FIG. 8 is a more detailed side cross-sectional illustration of a systemfor powering an electric vehicle 50 according to some embodiments of thepresent invention;

FIG. 9A is a schematic illustration of a circuit for changing theinductance of the receiver according to some embodiments of the presentinvention;

FIG. 9B is a graph illustration showing the frequency of the accumulatorchanges in a known range of modulation frequency, in known periods oftime, in a known time window, according to some embodiments of thepresent invention;

FIG. 10 is a schematic flow-chart illustration of a method for poweringa vehicle on a road according to some embodiments of the presentinvention;

FIG. 11 is a schematic flow-chart illustration of a method for poweringa vehicle on a road according to some embodiments of the presentinvention;

FIGS. 12A-12D are top views of power transmission line segmentsaccording to some embodiments of the present invention;

FIGS. 13A and 13B are schematic illustrations of receiver arrays on theunderneath of a vehicle according to some embodiments of the presentinvention;

FIG. 14 is a schematic illustration of a receiver circuit for energygathering from a receiver array according to some embodiments of thepresent invention;

FIGS. 15A-15F are schematic illustrations of the mechanical installationand structure of an power transmission line according to someembodiments of the present invention;

FIGS. 16A-16D illustrate schematically the dependency of the energytransmittance between accumulator coils and receiver coils on thelocation of a receiver array row above an power transmission linesegment according to some embodiments of the present invention;

FIG. 17 is a schematic illustration of an additional solution to preventradiance leakage from an power transmission line according to someembodiments of the present invention;

FIG. 18 is a schematic illustration of an additional solution to preventradiance leakage from an power transmission line and a receiver arrayaccording to some embodiments of the present invention;

FIGS. 19A and 19B are schematic illustrations of power transmission linesegments in a section of an power transmission line according to someembodiments of the present invention;

FIG. 20 is a schematic block diagram illustrating a system according tosome embodiments of the present invention;

FIG. 21 is a diagram illustrating some aspects relating to the coilsaccording to some embodiments of the present invention;

FIG. 22 is a diagram illustrating other aspects relating to the coilsaccording to some embodiments of the present invention;

FIG. 23 is a diagram illustrating yet other aspects relating to thecoils according to some embodiments of the present invention;

FIG. 24 is a diagram illustrating aspects relating to the base stationaccording to some embodiments of the present invention;

FIG. 25 is a diagram illustrating other aspects relating to the switchcard according to some embodiments of the present invention;

FIG. 26 is a diagram illustrating other aspects relating to the receiveraccording to some embodiments of the present invention;

FIG. 27 is a circuit diagram illustrating other aspects relating to thereceiver according to some embodiments of the present invention;

FIG. 28 is a circuit diagram illustrating other aspects relating to thereceiver according to some embodiments of the present invention;

FIG. 29 are waveform diagrams illustrating aspects relating to thereceiver according to some embodiments of the present invention; and

FIG. 30 is a circuit diagram illustrating other aspects relating to thereceiver according to some embodiments of the present invention.

It will be appreciated that, for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn accuratelyor to scale. For example, the dimensions of some of the elements may beexaggerated relative to other elements for clarity, or several physicalcomponents may be included in one functional block or element. Further,where considered appropriate, reference numerals may be repeated amongthe figures to indicate corresponding or analogous elements.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, and components,modules, units and/or circuits have not been described in detail so asnot to obscure the invention.

A system and method for charging an electric vehicle on a road,according to some embodiments of the present invention, may enablepowering a vehicle while moving on a road. Certain sections of a roadmay include a charge-inducing infrastructure, which may power a vehiclemoving upon it. Thus, the vehicle's chargeable battery may be used fortraveling in other road sections that does not include suchinfrastructure. For example, the size of the vehicle's chargeablebattery, which may be used for traveling in other road sections, may bereduced, and/or longer journeys may be enabled. In road sections thatinclude a charge-inducing infrastructure, the range of journey issubstantially unlimited, at least from the aspect of power.

Reference is now made to FIGS. 1A, 1B and 1C, which are schematic topview illustration and frontal cross-sectional view illustrations,respectively, of a system 100 for powering an electric vehicle accordingto some embodiments of the present invention. System 100 includes atleast one accumulator system 300 (described in more detail withreference to FIG. 5), two of which are shown in FIG. 1A. System 300includes an inductive stripe or power transmission line 20, which may beplaced on a road 30 or inside an excavated canal 32 in road 30, as shownin FIG. 1B. As shown in FIG. 2A, inductive stripe or power transmissionline 20 may include and/or perform as a primary winding of an air-coretransformer 200, wherein a secondary winding of transformer 200 may be areceiver array 10 installed at the vehicle underneath 52 of vehicle 50.Receiver array 10 may move from side to side along an axis Aperpendicular to the driving direction of vehicle 50 on road 30, and/orto the longitudinal axis of power transmission line 20.

Two tracking coils 13 may be installed at two sides of receiver array10, at the same distance from the center of receiver array 10 along axisA. Positioning of receiver array 10 by tracking coils 13 may beperformed by a closed-loop control method as described herein. In orderto receive power from power transmission line 20 efficiently, the centerof receiver array 10 along axis A, i.e. the center of a coil 17 (shownin FIG. 3A) along axis A, should be positioned above the center of powertransmission line 20, i.e., above the center of a coil 27 (shown in FIG.3A) along axis A. Accordingly, when receiver array 10 is at the desiredposition above power transmission line 20 for efficient powertransmission, two tracking coils 13 at respective two sides of receiverarray 10 should be positioned at the same distance from the center ofpower transmission line 20 along axis A. While a guiding signal and/orpowering signal is transmitted via an accumulator coil 27, as describedin detail herein, voltage values may be measured at the outlets oftracking coils 13. When receiver array 10 and tracking coils 13 areshifted off the desirable position above power transmission line 20,different average energy values may be measured at the outlets oftracking coils 13. The difference between the average energy values atthe two tracking coils 13 may be smaller as the shift from the desirableposition above power transmission line 20 is smaller, and the averageenergy values at the two tracking coils 13 may be substantiallyidentical when receiver array 10 and tracking coils 13 are positioned atthe desired position.

In some other embodiments, as shown in FIG. 1C, receiver array 10 mayinclude several receiver arrays 10 a, which may obviate the need to movethe receiver in order to receive the power from power transmission line20. System 100 may further include a generator or converter 22 that mayreceive power from a general electricity network and provide the powerrequired by power transmission line 20 in a respective road section. Onegenerator or converter 22 may be allocated to a certain road section ofbetween tens to hundreds of meters, depending on the number of lanes,the traffic load, the steepness of the road and/or any other parameterwhich may affect the power consumption of vehicles 50 and/or ofconverter 22.

According to some embodiments of the present invention, powertransmission line 20 may include a multi-phase power system, which mayoperate with one or more phases. It will be appreciated that in thepresent description, multi-phase power may include any number of one ormore phases, and may also refer, in some embodiments, to single-phasepower. Accordingly, any multi-phase system or element described hereinmay be or include a system or element of any number of one or morephases.

As shown in more detail herein below, power transmission line 20 mayinclude an array of accumulator units, wherein each unit may include anumber of sets of accumulator loads, e.g., accumulator coils, accordingto the number of phases, each set of coils receiving AC power in adifferent phase shift. Accordingly, multi-phase power transmission line20 may include a number of conductor groups 24 according to the numberof phases, to receive multi-phase AC power from converter 22 via thecorresponding multiple conductor groups 24.

Reference is now made to FIGS. 2A and 2B, which are cross-sectionalschematic illustrations of an air-core transformer 200 and 200 aaccording to some embodiments of the present invention. Powertransmission line 20 and receiver array 10 are shown. As shown in FIG.2A, receiver array 10 may move from side to side along an axis Aperpendicular to the driving direction of vehicle 50 on road 30, and/orto the longitudinal axis of inductive stripe 20, for example in order tobe positioned in a desired location above power transmission line 20according to signals measured at tracking coils 13. As shown in FIG. 2B,receiver array 10 may include in air-core transformer 200 a severalreceiver arrays 10 a, which may obviate the need to move the receiver inorder to receive the power from power transmission line 20. The numberof receivers along the width of vehicle 50 depends on the width of thevehicle.

As described in detail below, receiver array 10 or each of receiverarrays 10 a may constitute an array of receiver units, e.g., assembledof receiver coils, which may receive power from correspondingaccumulator coils. The width 1 of the work area, e.g. of each coil, ofreceiver array 10 or of each of receiver arrays 10 a, should be the sameas the width of power transmission line 20, e.g. the width of anaccumulator coil.

The size of the air middle gap, i.e., air core 210 between powertransmission line 20 and receiver array 10 may affect the ability oftransformer 200 to transfer energy. As the distance d between powertransmission line 20 and receiver array 10 is smaller, energy loses maybe smaller. The distance d may change within a known range during thejourney, for example, according to the bounces and/or the quality of theroad, which may affect movements of receiver array 10 along axis Z. Insome exemplary embodiments, the distance d between power transmissionline 20 and receiver array 10 may be of up to about 20 cm, wherein thewidth 1 of receiver array 10, e.g. of a receiver coil, may be of up toabout 40 cm. In order to neutralize the magnetic influences of thevehicle body, transformer 200 may include an insulator plate or plates12 between receiver array 10 or receiver arrays 10 a and the vehicleunderside 52.

Power losses of transformer 200 may be caused by the resistance of theconductors, for example of the receiver and accumulator coils, and bythe distance between power transmission line 20 and receiver array 10,which may depend, among other things, on the road conditions. Theresistance of the coils may be reduced by using suitable Litz wires.Losses caused by the distance between power transmission line 20 andreceiver array 10 may be smaller as the coils width is larger.

Additionally, a proximity effect may be created in the receiver andaccumulator coils. The proximity between the wires in a coil may causemutual swirl currents that may resist the current in the wires,especially at high frequencies. Embodiments of the present invention mayinclude spiral Litz coils made of one layer, enabling law interactionbetween proximate wires, thus reducing the proximity effect and/orproviding coils with high quality coefficient.

Transfer of energy may be provided, for example, when a receiver coil islocated above an accumulator coil, thus creating a transformer. Thepositioning of receiver array 10 or receiver array 10 a above powertransmission line 20 may be performed automatically by a closed-loopcontrol.

Reference is now made to FIGS. 3A and 3B, each showing side and bottomviews of multi-phase receiver units 15 in receiver 10 or receiver arrays10 a, respectively, according to some embodiments of the presentinvention. The number of cells or coils 17 in a receiver unit 15 dependson the power required by the vehicle. A multi-phase receiver 15, asincluded in typical embodiments of the present invention, may include atleast a number of coils 17 corresponding to the number of phases thesystem operates with, or any other multiple of this number. In anarrangement as shown in FIGS. 1C, 2B and 3B, the number of receiverarrays 10 a depends on the structure and width of the vehicle.

Reference is now made to FIG. 4, which is a schematic illustration ofside, top and bottom view of multi-phase power transmission line 20,according to some embodiments of the present invention. Powertransmission line 20 may be formed of segments of a few tens of meters.Each segment may constitute a few sections 25 of about one meter. Eachsection 25 may be powered separately by a corresponding multi-phasepower generator such as generator 22. Each section 25 may include anumber of accumulator loads, e.g. accumulator coils 27, according to thenumber of phases or another multiple of this number. For example, athree-phase power transmission line 20 may be powered by a correspondingthree-phase power generator such as generator 22. Accordingly, eachsection 25 may include three accumulator loads, e.g. accumulator coils27, or another multiple of three, such as six accumulator loads. In theexample of FIGS. 4-7, a three-phase configuration is shown, although theinvention is not limited in that respect. The embodiments shown in FIGS.4-7 may operate with any other number of phases of power. Accordingly,whenever the description mentions three elements or multiple of threeelements that correspond to the three phases of power, it may bereplaced with another number of system elements according to the numberof phases the system operates with, or a multiple of this number,respectively.

As shown in FIG. 4, coils 27 are assembled with at least partial overlapone upon the other, and/or connected by a triangle connection. Thedirection of the windings in coils 27 in each section may be the sameand thus the magnetic field may have the same phase along each section25. Coils 27 may include three groups of coils, the coils in each groupreceive AC power with the same phase shift and may be connected inparallel to each other. Each group may receive AC power with a differentphase shift from generator 22. The power may be received via threegroups of conductors 24 a, 24 b and 24 c, corresponding to the threegroups of coils (or another number of groups according to the number ofphases), each group of conductors conducting AC power with a differentphase shift from generator 22, so that each of the three (or anothernumber of) groups of coils receives power from another one of the threegroups of conductors transmitting power with a particular phase shift.Each section 25 may include one coil of each group of coils, so thateach section 25 constitutes a three-phase load in the present example.

According to one embodiment of the present invention, in a three-phaseconfiguration, each section 25 may include three coils, for example withthe same current direction in all three coils 27, which may be arrangedwith a partial overlap one over the other. A schematic illustration ofthe electrical arrangement of such three-coil section is shown in FIG.6A.

According to further embodiment of the present invention, in athree-phase configuration, each section 25 may include six coils 27, forexample with alternating current directions. The six coils may bearranged, for example so that each coil 27 overlaps half of a next coil27. Two overlapping coils 27 in this arrangement may have oppositecurrent directions. This arrangement may be more expensive. However, itmay provide a more magnetic flux and more uniform and intense power. Inboth embodiments the overlap regime between coils 27, e.g., thepositioning and measure of overlap, and the overlap regime betweenreceiver coils 17, is substantially identical. A schematic illustrationof the electrical arrangement of such six-coil section 27 is shown inFIG. 6B.

Reference is now made to FIG. 5, which is a schematic cross-sectionalillustration of an accumulator system 300 according to some embodimentsof the present invention. Accumulator system 300 may include powertransmission line 20 embedded in road 30. Power transmission line 20 maybe placed within a canal 32 in road 30. Power transmission line 20 mayinclude three groups of conductors 24 a, 24 b and 24 c and coils 27arranged with at least partial overlap one over another. Within canal32, accumulator system 300 may include insulator casting 29 to insulatepower transmission line 20, for example from all sides except the top ofcoils 27, for example, in order to enable power transmission line 20 totransfer power via the top of coils 27 exclusively. Accumulator system300 may further include, for example, an adhesive layer 26, to attach alayer 33 of stones or asphalt upon power transmission line 20.

Reference is now made to FIGS. 6A, 6B, 6C and 6D. FIGS. 6A and 6B areschematic illustrations of electrical arrangements 400 a and 400 b of athree-coil section 25 and of a six-coil section 225, respectively. FIGS.6C and 6D are top view of a three-coil section 25 and of a six-coilsection 225, respectively. Each of electrical arrangements 400 a and 400b may include a generator 22, which may include a three-phase inverter21, which may invert, for example, single-phase alternating powerreceived from a general electricity network to three-phase power, e.g.,to three power transmissions, each with a different phase shift.Alternatively, generator 22 may receive power from a three-phase centralelectricity network. Additionally, generator 22 may include an adaptor23 that may route the three-phase power to the three groups ofconductors 24 a, 24 b and 24 c, so that each group of conductorsconducting power with a different phase shift. In FIG. 6A, the threecoils 27 in each section 25 may have the same current direction, asshown in FIG. 6C. In FIG. 6B, the three coils 27 in section 25 a mayhave the same current direction, while the three coils 27 in section 25b may have the same current direction, opposite to the current directionin section 25 a, as shown in FIG. 6D. The three coils 27 in each ofsections 25 a or 25 b are connected by a triangle connection, andreceiving the three-phase power via the three groups of conductors 24 a,24 b and 24 c.

In some embodiments of the present invention, a single-phaseconfiguration may be used. Reference is now made to FIG. 7, which is anunderneath view schematic illustration of a single-phase receiver array10 a and a single-phase power transmission line 20 a according to someembodiments of the present invention, which may replace receiver array10 and power transmission line 20 in some embodiments of the presentinvention described herein. Single-phase receiver array 10 a may includeone or more single receiver coils 17 a, each constituting a receiverunit 15 by itself. Power transmission line 20 may include singlephase-accumulator sections 255, which may replace accumulator sections25 in some embodiments of the present invention described herein, eachmay include a number of accumulator coils, for example three coils asshown in FIG. 7. The width of a single receiver coil 17 may conform tothe width of the entire accumulator section 25. Each accumulator section25 may include the number of accumulator coils connected in parallel andmay have two outlet conductors. This arrangement may reduce the receivercosts. Additionally, because of the large size receiver coil 17 a, thepower reception may be less sensitive to the positioning of receiverarray 10 along axis A and along axis Z.

Reference is now made to FIG. 8, which is a more detailed sidecross-sectional illustration of a system 100 for powering an electricvehicle 50 according to some embodiments of the present invention.System 100 may include power transmission line 20 including sections 25,on or within road 30. System 100 may further include generator 22,coordination capacitors 84, communications unit 82, three-phase powersupply 90, and three groups of conductors 24 a, 24 b and 24 c asdescribed in detail herein. System 100 may further include, installed invehicle 50, a receiver array 10 including at least two tracking coils13, at least one three-phase receiver 15, an accelerometer 19 and acommunications coil 18. Additionally, system 100 may include, installedin vehicle 50, coordination capacitors 64, communications unit 62,diode-bridge 66, super-capacitor 68, accumulator 70 and engine/inverter72. Accelerometer 19 may detect movements of receiver array 10 alongaxis Z.

The power received by receiver array 10 may be converted to DC power andmay be transmitted to accumulator 70 which may store some energy, and toengine/inverter 72, which may drive the car. Accumulator 70 in car 50may be used as backup energy source, for example when there is nosufficient and/or available accumulator infrastructure in the road, orwhen the car deviates from a lane. In some embodiments, the powerprovided by power transmission line 20 in the road may not suffice forriding on an ascending road, and the additional energy needed may beprovided by accumulator 70.

Super capacitor 68 may enable aggregation of significant amount ofenergy in relatively short time. Super capacitor 68 may aggregate powerwhen the vehicle decreases its velocity. For example, super capacitor 68may aggregate all the energy released during sudden breaking of vehicle50 from velocity of 100 KM/h. Super capacitor 68 may store energyaggregated during breaking of vehicle 50. The energy stored in supercapacitor 68 may be utilized, for example, in situations whensupplementary energy is required. For example, energy stored in supercapacitor 68 may be utilized for acceleration of vehicle 50. In someembodiments of the present invention, excess energy may be returned backvia receiver array 10 to power transmission line 20 and then back to ageneral electricity system or to generator 22, for example to powerother vehicles on power transmission line 20, to provide power to roadlights, and/or for any other suitable use.

In order to enable positioning of receiver array 10 relative to powertransmission line 20, for example in axis A perpendicular to the drivingdirection, generator 22 may produce and/or transmit via powertransmission line 20 a guiding signal. The production and/ortransmission of the guiding signal may be performed before fullinitiation of generator 22 and/or full transmission of power bygenerator 22. For example, a designated generator of low power mayconstantly operate in the background and transmit the guiding signal,synchronized with generator 22 signaling, via the corresponding section25. In another embodiment, generator 22 may include a switch 86 that maychange the mode of operation of generator 22 from full transmission modeto guiding signaling mode, for example when no receiver is detectedabove the accumulator coils, and from guiding signaling mode to fulltransmission mode, for example, when receiver array 10 is detected abovethe accumulator coil. For example, before initiation of full powertransmission to receiver array 10, the current from generator 22 may beprovided to section 25 via a reactive component, such as, for example, acoil with at least ten times the inductance of a coil 27, or a capacitorsmall enough in order to avoid a resonance frequency of powertransmission line 20. An AC switch 86 may short the reactive componentwhen required, e.g., when receiver array 10 is properly located and mayreceive power according to some embodiments of the present invention, sothat the power from generator 22 may be transmitted to section 25 andinduced to receiver array 10 without the impedance of the reactivecomponent. Full initiation of generator 22 and/or full powertransmission by generator 22 means that generator 22 transmits power forpowering vehicle 50, as opposed to the law-power guiding signaldescribed herein, which is transmitted for initial positioning ofreceiver array 10.

The guiding signal may be received via two or more tracking coils 13,which may be located at the sides of receiver array 10. The guidingsignal may be received by tracking coils 13 via a correspondingaccumulator coil 27 and may be used for positioning of receiver array 10above power transmission line 20 according to some embodiments of thepresent invention. Once receiver array 10 is positioned above powertransmission line 20 in a sufficiently accurate manner, identificationsignal may be sent to communications unit 82, for example viacommunication coil 18.

For example, when the average energy values are the same at the twotracking coils 13, i.e., when receiver array 10 is positioned in thedesired position above power transmission line 20 for efficient powertransmission, communications unit 62 may transmit an identificationsignal to power transmission line 20 via communications coil 18 in orderto initialize the power transmission, as described in detail herein.

Communications coil 18 may be located at the front of the receiver array10 in the driving direction B of the vehicle. Communications coil 18 mayenable communications with generator 22 and/or with an operator ofsystem 100. For example, identification may be required foridentification of the vehicle, debiting of a subscriber and initiationof the generator.

Communications coil 18 may be attached in the front of receiver array 10in the driving direction B as shown in FIG. 8. Communications coil 18may have, for example, two windings. Communications coil 18 may workwith modulation frequency of about 1-10 MHz. An identification signalmay be transmitted by communication unit 62 via communication coil 18and induced to accumulator coils 27 and received by communication unit82 in generator 22 and may be transmitted further to signal processing.In case the identification signal from communications coil 18 isidentified, the relevant section 25 may be operated and become theoperative section 25, e.g. the section 25 above which a correspondingsection 15 is located, for example by a corresponding AC switch 86 asdescribed above, and may transmit power by inductance to section 15.This may happen when a section 15 is above a section 25 and atransformer 200 is formed of an accumulator coil 27 and a receiver coil17. Additionally, an adjacent section 25, e.g., the next section 25 inthe driving direction B of vehicle 50 may also be operated, in order tobe ready to transmit power to receiver array 10 when section 15 reachesa location above the next section 25. Therefore, two sections 25 areoperated once an identification signal from communications coil 18 isidentified. As vehicle 50 progresses in direction B, a section 25 maycease receiving and/or inducing full power, e.g. except a guidingsignal, once there is no recognition of a receiver section 15 above thesection 25. For example, the ceasing may be performed by thecorresponding AC switch 86 as described above, which may open the shortcircuit, thus only low power guiding signal from generator 22 may betransmitted to section 25, via the reactive component. The recognitionof whether a receiver section 15 is above the section 25, may beperformed by checking the current through the section 25, whichtypically will have a different form when inducing power to receiverarray 10 and when not. Once the section 15 is identified by the nextsection 25, the next section 25 becomes the operative section, and thesection 25 after the operative section 25 in the driving direction mayalso be initiated as discussed, and so on.

When the air core 210 between receiver array 10 and power transmissionline 20 is relatively large, e.g., distance d between power transmissionline 20 and receiver array 10 is greater than a quarter of width 1, thepower loses may be high. In order to overcome the high power loses andmake the power transmission more efficient, receiver array 10 mayoperate in resonance, for example following the frequency dictated bygenerator 22. In order to raise the efficiency of power transmission,power transmission line 20 may work in sub-resonance. For example, acapacitor 84 may be connected in series to a section 25, which may havea greater capacity than required for having the same resonance frequencyof receiver array 10. Thus, for example, the resonance frequency ofpower transmission line 20 may be smaller than, for example 80 percentof, the resonance frequency of receiver array 10. A magnetic field in acoil develops proportionally to the current intensity and to the numberof windings. In order to create a sufficiently intense magnetic field,the inductance of the coil may be increased by increasing the number ofwindings, which may require increase of the voltage. Additionally, thismay require very thin coil wires, while the insulation may have to bethick. Alternatively, in order to create a sufficiently intense magneticfield, the current may be increased by increasing the width of the coilwires. However, working with high current may require thick conductorswhich may increase the costs of the system. Working in resonance intransformer 200, for example by addition of suitable capacitors inseries to power transmission line 20 and/or receiver array 10, maycreate very high intensity currents and, therefore, the magnetic fieldmay increase dramatically as well, while the system may become unstableand hard to control. However, working in sub-resonance state in powertransmission line 20 may increase the current and the magnetic fieldwhile increasing the efficiency. Therefore, a suitable capacitor 84should be inserted in order to keep the system stable.

The distance between receiver array 10 and power transmission line 20may change during the travel, which may affect changes in the mutualcoupling coefficient of air transformer 200. Changes in the couplingcoefficient may affect the resonance frequency. Accordingly, a smallerdistance d between receiver array 10 and power transmission line 20, mayincrease the resonance frequency of transformer 200 and a largerdistance d may decrease the resonance frequency of transformer 200,e.g., relative to the operation resonance frequency of receiver array10. A horizontal movement of receiver array 10 relative to powertransmission line 20 may also decrease the resonance frequency oftransformer 200, e.g., relative to the operation resonance frequency ofreceiver array 10. These changes in the resonance frequency oftransformer 200 relative to the operation resonance frequency ofreceiver array 10 may decrease the power transmission via transformer200.

Some embodiments of the present invention provide solutions to changingroad conditions to prevent and/or moderate the decrease in the powertransmission because of changes in the resonance frequency. In order tomaximize the power transmission, the inductance of receiver array 10 maybe changed by a regulation circuit 500 shown in FIG. 9A. Transformer K4may add inductance of up to 1 percent to coil 17 of receiver array 10.The inductance addition may decrease the resonance frequency of receivercoil 17. Switches M3 to M7 may connect or disconnect inductors, thusadding or subtracting inductance values to or from the inductance oftransformer K4. Therefore, the resonance frequency of coil 17 may becontrolled and/or regulated to conform to the resonance frequency oftransformer 200 and/or the frequency of power transmission line 20.

Additionally, receiver array 10 may include an accelerometer 19 (shownin FIG. 8) that may detect changes in height, e.g. vertical movements,e.g. movements toward the ground (along axis Z), in real time duringtravel. Two tracking coils 13 described above may detect in real timeshifts of the receiver, e.g., horizontal movements of receiver array 10relative to power transmission line 20. When such movements aredetected, the resonance frequency of coil 17 may be controlled,calibrated and/or regulated by circuit 500 as described herein.

In some embodiments of the present invention, the calibration of theresonance frequency of coil 17 may be performed by the frequency ofpower transmission line 20. In known periods of time, in a known timewindow, the frequency of power transmission line 20 may be changed in aknown range of modulation frequency. For example, as Shown in FIG. 9B,the accumulator frequency may change every 100 ms, in a 1 ms timewindow, from 100 kHz to 101 kHz, from 101 kHz to 99 kHz and from 99 kHzback to 100 kHz. During this time window of 1 ms, receiver array 10 maybe calibrated to the optimal frequency resulting in maximal energytransmission, by adding/subtracting inductance by circuit 500 asdescribed above, according to the difference between the operationresonance frequency of receiver array 10 and the optimal frequency. Thiscalibration may hold until the next time window of 1 ms.

Each generator 22 may account for a certain segment of the road of a fewtens of meters, for example up to about hundred meters. Such segment mayinclude tens of sections 25, for example, the length of each may be ofabout one meter. Each generator 22 may be required to generate at least100 KW, for example for a bi-directional, four lanes road segment, onwhich about ten cars are moving at a given moment at about 100 km/h,each car requiring about 10 KW. The generator may provide a square orsinus wave at about 400 KHz or less and alternating voltage of about1000 v or less.

A breaking vehicle, i.e., a vehicle which decreases its velocity, mayoperate as a generator and may provide power to the power transmissionline 20, for example in case its own accumulator 70 is full. Whenvehicle 50 decreases its velocity, the excess power may be provided backto accumulator coils 27. This may be an efficient arrangement, whereinvehicles moving down the road may provide power to the vehicles movingup the road, thus less total energy may be consumed from generator 22.An accumulator section 25 without a receiver section 15 above it, whichmay constitute a transformer without a load, may consume substantiallyno energy except occasional loses and the guiding signal. Additionally,for safety reasons, an accumulator section 25 may be operated, e.g.,receive full power from generator 22, only when a corresponding receiversection 15 is located over it. In case of a resonance when receivercoils 17 are above the corresponding accumulator coils 27, highintensity currents and strong magnetic fields may develop. However,these magnetic fields become negligible in a distance of about 20 cmfrom the operative section 25.

In order to connect to the power transmission line 20, e.g., communicatewith and identified by communications unit 82, the vehicle must movewhile power transmission line 20 is between the wheels. The exactpositioning of the receiver array 10, i.e., by moving receiver array 10along axis A perpendicular to the driving direction, may be performedautomatically and dynamically. In case of a receiver array 10 includingseveral receiver arrays 10 a, the transmission between powertransmission line 20 and receiver array 10 may be performedcontinuously.

Reference is now made to FIG. 10, which is a schematic flow-chartillustration of a method for powering a vehicle on a road according tosome embodiments of the present invention. As indicated in block 810,the method may include producing multi-phase power of at least one phaseby a multi-phase generator of a least one phase. As indicated in block820, the method may include receiving multi-phase power from themulti-phase generator by an power transmission line installed in a road,the power transmission line includes a series of accumulator sections,each section includes at least a number of accumulator coilscorresponding to the number of phases, and each of the coils may beconfigured to receive power with a different phase shift. The method mayfurther include carrying the power by a number of groups of conductorscorresponding to the number of phases, each group carrying power with adifferent phase shift from the multi-phase generator to the powertransmission line. As indicated in block 830, the method may includereceiving a signal at a communications unit from a communications coilin a vehicle located above at least one of the accumulator sections. Asindicated in block 840, the method may include operating correspondingaccumulator sections to provide power to a receiver attached to thevehicle.

In some embodiments, the method may further include providing by thegenerator a guiding signal to be transmitted to the receiver at thevehicle via the accumulator.

In some embodiments, the method may further include operating by thecommunications unit a next accumulator section in the driving directionof the vehicle, before the receiver at the vehicle reaches a locationabove the next section.

In some embodiments, the method may further include ceasing oftransmitting full power by the generator to a specific accumulatorsection once there is no recognition of a receiver above the specificsection.

In some embodiments, the method may further include powering eachaccumulator section separately by a corresponding multi-phase powergenerator.

In some embodiments, the method may further include changing the mode ofoperation of the generator by a switch from full transmission mode toguiding signaling mode when no receiver is detected above theaccumulator coils, and vice versa when the receiver is detected abovethe accumulator coils.

Reference is now made to FIG. 11, which is a schematic flow-chartillustration of a method for powering a vehicle on a road according tosome embodiments of the present invention. As indicated in block 910,the method may include receiving multi-phase power of at least one phaseby a receiver array installed beneath a vehicle, the receiver arrayincludes at least one multi-phase receiver including at least a numberof receiver coils corresponding to the number of phases, for example atleast one receiver coils, from corresponding accumulator coils installedin a road, while the vehicle moves on the road above the accumulatorcoils.

As indicated in block 920, the method may include sending anidentification signal to a communications unit via a corresponding oneof the accumulator coils, by a communications coil located in front ofthe receiver array in the driving direction of the vehicle.

In some embodiments, the method may further include receiving by each ofthe receiver coils power with a different phase shift from acorresponding accumulator coil.

In some embodiments, the method may further include receiving, by atleast two tracking coils at two sides of at least one of the multi-phasereceivers, positioned in equal distances from the center of the at leastone of the multi-phase receivers, a guiding signal via a correspondingone of the accumulator coils, and positioning the receiver array abovethe accumulator coils according to average energy measured at least twotracking coils.

In some embodiments, the method may further include providing by thereceiver array excess power back to the accumulator coils when thevehicle decreases its velocity.

In some embodiments, the method may further include aggregating power bya super capacitor when the vehicle decreases its velocity.

In some embodiments, the method may further include changing by aregulation circuit the inductance of each of the receiver coils toconform to the resonance frequency the accumulator section by aregulation circuit, the regulation circuit including a transformer toadd inductance to the receiver coil and switches to connect ordisconnect inductors to change inductance values of the transformer.

In some embodiments, the method may further include detecting in realtime vertical and horizontal movements of the receiver array, whereinsaid regulation circuit may regulate the resonance frequency of thereceiver coil when movements are detected.

Power transmission line 20 may receive power from a central power systemand return power from system 100 to the central power system, such asthe national and/or local power system. As discussed in detail herein,each receiver coil 17 may be configured to receive power from acorresponding accumulator coil 27 while vehicle 50 moves on the roadabove corresponding accumulator coil 27, and further to provide excesspower back to power transmission line 20. The excess power may bereturned to the central power system and/or be provided to othervehicles by power transmission line 20. Therefore, power transmissionline 20 may perform as an energy source as well as an energyaccumulator. As such, for example, accumulator 20 may be required tofulfill radiation safety requirements.

Reference is now made to FIGS. 12A-12D, which are top views of powertransmission line segments 227 or 227 a, according to some embodimentsof the present invention. Power transmission line segments 227 or 227 amay be suitable for a one-phase configuration of embodiments of thepresent invention, i.e., coils 27 of power transmission line segment 227or 227 a may receive power at the same phase. Power transmission linesegment 227, i.e., a segment of power transmission line 20, may includefour coils in some exemplary embodiments. In some other exemplaryembodiments, the segment may include two coils as in segment 227 a shownin FIG. 12C. In other embodiments, power transmission line segment 227may include any other suitable number of coils. In some embodiments ofthe present invention, two adjacent accumulator coils 27 may haveopposite current direction, as shown by arrows w and w′ in FIGS.12A-12D. According to some embodiments of the present invention, anarrangement where two adjacent accumulator coils 27 have oppositecurrent direction may facilitate significant reduction of radiation frompower transmission line 20 and thus a safer system 100.

By having two adjacent accumulator coils 27 that have opposite currentdirection, the magnetic fields 260 created by the two adjacent coils 27may fade each other as the distance Dm from the longitudinal axis ofpower transmission line 20 is greater outside the area of powertransmission line 20. This fading may not harm the energy transfer frompower transmission line 20 to receiver array 10 and from receiver array10 to power transmission line 20. Therefore, in such embodiments, eachtwo adjacent coils 27 may fade the magnetic fields of each other. Oneproblem that may occur in such arrangement is that the energy transfermay be uneven, with intensity drops 265 at the transition areas betweentwo adjacent coils 27, for example where two adjacent coils 27 meet. Insome embodiments of the present invention, in order to overcome theseintensity drops, a capacitor may be installed in connection to receiverarray 117 (not shown), for example, a supercapacitor, that may smoothand mediate the power received from power transmission line 20.

As mentioned above, in some exemplary embodiments, power transmissionline segment 227 may include four coils 27, as shown in FIGS. 12A, 12Band 12D. The length of such power transmission line segment 227 may beof about 100-130 cm. The interface points between coils 27 enhance themutual inductance of adjacent coils 27, and, therefore, the generalinductance of power transmission line segment 227 and/or of subsequentpower transmission line segments 227. FIG. 12B shows three subsequentpower transmission line segments 227.

FIGS. 12C and 12D show the manner of coiling of wires 275 of coils 27 inseries-connected subsequent coils 27 in power transmission line segments227 a and 227, respectively, and the manner of connection betweenseries-connected subsequent coils 27 by conductors 238. Transitionsbetween subsequent or preceding power transmission line segments 227 aor 227 are shown by arrows 237 that depict connections with subsequentor preceding power transmission line segments 227 a or 227. Thetransitions between subsequent or preceding power transmission linesegments 227 a or 227 are characterized by a large potential difference,which requires enhanced electrical isolation. This manner of coiling andconnection may be similar for coils 17 of receiver arrays 117 and 117 ashown in FIGS. 13A and 13B.

Reference is now made to FIGS. 13A and 13B, which are schematicillustrations of receiver arrays 117 and 117 a on the underneath of avehicle 50, respectively, according to some embodiments of the presentinvention. Receiver arrays 117 may include a number of rows 127, eachconstitutes an array of receiver coils 17. A row 127 may include anysuitable number of receiver coils 17, for example according to thelength of vehicle 50 and/or any other suitable considerations.Additionally, a row 127 may include a communications coil 18 that may belocated at the front of the receiver coils 17 in the driving direction Bof the vehicle. Receiver array 117 may include any suitable number ofrows 127, for example according to the width of vehicle 50 and/or anyother suitable considerations. In accordance with the power transmissionline segments 227 or 227 a, receiver array 117 may be suitable for aone-phase configuration of embodiments of the present invention.Accordingly, two adjacent receiver coils 17 in row 127 may have oppositecurrent direction, for example as shown by arrows w and w′, and/or coils17 of an array 117 may be connected in series, for example, similarly tothe coiling and connection of accumulator coils 27 of power transmissionline segment 227 or 227 a shown in FIGS. 13C and 13D.

Alternatively, a receiver array 117 a may include a series of oval orrectangular series-connected oblong receiver coils 17 a, wherein twoadjacent receiver coils 17 a may have opposite current direction, forexample as shown by arrows w and w′. The width of oblong receiver coils17 a may be determined according to the width of vehicle 50 and/or anyother suitable considerations. Receiver array 117 a may also include,for example, an oblong communications coil 18 a that may be located atthe front of the receiver coils 17 a in the driving direction B of thevehicle.

Reference is now made to FIG. 14, which is a schematic illustration of areceiver circuit 700 for energy gathering from receiver array 117 or 117a according to some embodiments of the present invention. Circuit 700may include, for example, two coils L1 and L2 connected in series,although any other suitable number of coils may be included. Coils L1and L2 may represent the inductances of two subsequent coils 17 (or 17a) in array 117 (or 117 a), having inductances L1 and L2, respectively.Coils L1 and L2 may be connected in parallel to capacitors C16, C19 andC17, as shown in circuit 700, wherein capacitors C16 and C19 areconnected in series and have together an equivalent capacitance C1. Theenergy, i.e. the outlet voltage, may be collected by capacitor C18 viadiode bridge D1. The resonance frequency of circuit 700 in this case maybe approximately inversely proportional to the square root of(L1+L2)·(C17+C1).

Circuit 700 may further include a mechanism for regulating the resonancefrequency of receiver circuit 700 according to the load requirements,for example the requirements of engine/inverter 72 of vehicle 50.According to some embodiments of the present invention, the energyreceived via receiver coils 17 is provided directly to powerengine/inverter 72 and not to charge a battery or another power storagedevice, except for a small portion of the energy stored for a back-up,for example in accumulator 70. Usually, the resonance frequency ofreceiver circuit 700 is higher than the resonance frequency of powertransmission line segment 227 (or 227 a), and, therefore, the energytransfer between receiver array 117 or 117 a and power transmission linesegment 227 (or 227 a) may not be optimal. Therefore, circuit 700 mayinclude a pulse-width modulator (PWM) controller 710, a switch S1 and anadditional capacitor C20, which may be connected in parallel tocapacitor C19 when switch S1 is closed. PWM controller 710 may sensewhen the load needs more power and when the load needs less power. Whenswitch S1 is open and PWN controller 710 senses that the load needs morepower, it may close switch S1. Since closing switch S1 adds capacitor 20in parallel to capacitor C19, the resonance frequency of receivercircuit 700 may be reduced to the resonance frequency of powertransmission line segment 227 (or 227 a), which may improve the energytransfer and increase the outlet voltage at capacitor C18. When switchS1 is closed and PWN controller 710 senses that the load needs lesspower, it may open switch S1 and thus, for example, capacitor C20 willbe disconnected. When capacitor C20 is disconnected, the resonancefrequency of receiver circuit 700 may be increased above the resonancefrequency of power transmission line segment 227 (or 227 a), which mayreduce the outlet voltage at capacitor C18. The regulation by PWMcontroller 710 may be performed dynamically and in a sufficient speed toprovide sufficient stability of power supply. Switch S1 should be stableenough to bear the high voltage differences.

Reference is now made to FIGS. 15A-15F, which are schematicillustrations of the mechanical installation and structure of powertransmission line 20, according to some embodiments of the presentinvention. Power transmission line 20 may be mechanically andelectrically protected and sealed against humidity and/or dampness.Power transmission line 20 may be constructed from power transmissionline basic installation units 250 as described in detail herein.

FIGS. 15A and 15B are schematic illustrations of power transmission linebasic installation units 250, according to some embodiments of thepresent invention. Basic installation unit 250 may be a monolithic unitand/or may include an power transmission line segment 227 (or 227 a), asshown in FIG. 15A, or several power transmission line segments 227 (or227 a), as shown in FIG. 15B, and conductors 240 coming out of one end251 of unit 250, to conduct current to segments 227 (or 227 a) and/orfrom segments 227 (or 227 a). Basic installation unit 250 may be includeseveral power transmission line segments 227 (or 227 a), as shown inFIG. 15B, for example three power transmission line segments 227 (or 227a) or any other suitable number of power transmission line segments 227(or 227 a). Basic installation units 250 may be placed sequentially in arow within canal 32 in road 30.

FIGS. 15C and 15D are schematic illustrations of an above view and afrontal cross-sectional view, respectively, of the structure andinstallation 600 of power transmission line 20 according to someembodiments of the present invention. Installation 600 may include canal32, which may be ditched in road 30. Basic installation units 250 may beplaced sequentially within canal 32. For example, the first installationunit 250 may be put in the distal end of the canal relative to generator22 described in detail herein, e.g., in the end of canal 32 far fromgenerator 22. Conductor 240 coming out of one end of unit 250 may beplaced in canal 32 in the direction of generator 22. For example, theend 251 of unit 250 from which conductor 240 comes out, is placed in thedirection of generator 22. For example, the distal end of conductor 240relative to unit 250 may reach generator 22. Each subsequent unit 250may be placed on conductor(s) 240 of the previous unit(s), adjacent tothe previous unit 250 and in the same orientation, i.e., so that the endof unit 250 from which conductor 240 comes out, is placed in thedirection of generator 22, and/or so that conductor 240 coming out ofone end of unit 250 may be placed in canal 32 in the direction ofgenerator 22. In this manner, units 250 may be placed one after theother, from the distal unit 250 relative to generator 22 to the proximalunit 250 relative to generator 22. The distal ends of conductors 240,relative to units 250, may reach generator 22.

As shown in FIG. 15D, within canal 32, installation 600 may includeinsulator casting 29 to insulate power transmission line segment 227 (or227 a), for example from all sides except the top of coils 27, forexample, in order to enable power transmission line 20 to transfer powervia the top of coils 27 exclusively. Installation 600 may furtherinclude, for example, an adhesive layer 26, to attach a layer 33 ofstones or asphalt upon power transmission line 20. Conductors 240 comingout of units 250 may be placed one adjacent to the other, electricallyisolated one from another, and in an ordered cluster in order to preventloops and/or intertwining of the conductors wires.

FIGS. 15E and 15F are schematic illustrations of a detailed above viewand a longitudinal cross-sectional view, respectively, of the structureand installation 600 of basic installation units 250, including powertransmission line segment 227 and a conductor 240, according to someembodiments of the present invention. Power transmission line segment227 may be placed, for example, between two surfaces 270 ofpolycarbonate or any other suitable insulating and/or waterproofmaterial, which do not reduce the inductance significantly.Additionally, power transmission line segment 227 may be surrounded inits periphery by a seal 271, which may seal power transmission linesegment 227 against humidity and voltage outbreaks. The distances 1between coils 27 may be determined by taking into account the electricpotential, in order to prevent voltage outbreaks. Subsequent coils 27within segment 227 may be connected to each other by conductors 238, forexample in the manner shown in FIG. 8D.

Reference is now made to FIGS. 16A-16D, which illustrate schematicallythe dependency of the energy transmittance between accumulator coils 27and receiver coils 17 on the location of receiver array row 127 abovepower transmission line segment 227, according to some embodiments ofthe present invention. FIGS. 16A and 16B are schematic illustrations ofreceiver array row 127 and power transmission line segment 227 accordingto some embodiments of the present invention. For example, a receiverarray row 127 may include two receiver coils 17 and a conductor 138,connecting the two coils 17 in series. When vehicle 50, with receiverarray 117 in its bottom, passes above power transmission line segment227 in the driving direction B, sometimes receiver coils 17 may bealigned above corresponding accumulator coils 27, for example as shownin FIG. 16A, so that the energy transmittance may be maximal, andsometimes receiver coils 17 may be located above the transition areasbetween two subsequent accumulator coils 27, for example as shown inFIG. 16B, where the energy transmittance may be reduced. FIG. 6C is aschematic graph illustration 1600 a of the energy transmittance versusthe location of receiver array row 127 above power transmission linesegment 227. As shown in graph illustration 1600 a, the energytransmittance may be uneven along power transmission line segment 227.FIG. 6D shows a schematic graph illustration 1600 b of the energytransmittance versus the location of receiver array row 127 above powertransmission line segment 227, mediated by a capacitor. As shown bygraph illustration 1600 b capacitor connected to receiver array row 127may reduce the energy transmittance differences along power transmissionline segment 227 shown in graph illustration 1600 a.

As discussed herein, some embodiments of the present invention mayprovide solutions to prevent radiance leakage from power transmissionline 20. As mentioned above, by having adjacent coils with oppositecurrent directions and thus, for example, opposite magnetic fields, themagnetic field fades outside the area of power transmission line 20 andbecomes stronger within the area of power transmission line 20. Thissolution is suitable, for example, for embodiments of the presentinvention that use single-phased power.

Reference is now made to FIG. 17, which is a schematic illustration ofan additional solution to prevent radiance leakage from powertransmission line 20, according to some embodiments of the presentinvention. Power transmission line 20 may have opposite coil windings 28around accumulator coil 27, with an opposite current direction to thecurrent direction in coil 27. The opposite current direction in oppositecoil windings 28 reduces the magnetic field around coil 27.

Reference is now made to FIG. 18, which is a schematic illustration ofan additional solution to prevent radiance leakage from powertransmission line 20 and receiver array 10 or 117 (or 117 a), accordingto some embodiments of the present invention. In some embodiments of thepresent invention, protecting materials may be used in order to channeland/or screen the magnetic fields. For example, receiver array 10 or 117(or 117 a) may include an aluminum foil 11 between insulator plate andthe bottom of vehicle 50, wherein aluminum foil 11 includes reminders 11a that are folded down to the sides of receiver coil 17. The magneticflow created by accumulator coil 27 under layer 33 of stones or asphaltgo up as shown by arrows h through receiver coil 17 and induce current.Than the magnetic flow meets insulator plate 12, turns, as shown byarrow I, and proceeds down, as shown by arrows j, to close the magneticfield loop as shown by arrows k. However, a portion of the magnetic flowpenetrates through the insulator plate 12 and turns to heat and thus,for example, creating vortex flows, shown by arrows p, in aluminum foilreminder 11 a. As the aluminum foils reminders 11 a are longer, i.e.,get lower, the magnetic flow leakage may be smaller.

Reference is now made to FIGS. 19A and 19B, which are schematicillustrations of power transmission line segments 227 in a section ofpower transmission line 20, according to some embodiments of the presentinvention. In FIGS. 19A and 19B, each power transmission line segments227 may include three accumulator coils 27, although the invention is nolimited in that respect. Subsequent power transmission line segments 227i and 227 j are electrified, i.e., receive power from generator 22. Eachtwo subsequent accumulator coils 27 have an opposite current direction,as shown by arrows w and w′. Current direction w is opposite to currentdirection w′. Therefore, the magnetic fields of two subsequentaccumulator coils 27 fade each other outside the area of the coils,except the magnetic fields of the extreme coils 27 i and 27 j which arelocated in the extremes of the electrified section of power transmissionline 20, which includes subsequent power transmission line segments 227i and 227 j. The magnetic fields of extreme coils 27 i and 27 j do notfade, and thus constitute sources of residual radiation 900.

According to some embodiments of the present invention, powertransmission line 20 may include guard rings 800, wherein each guardring 800 surrounds the two adjacent extreme coils 27 of two subsequentpower transmission line segments 227, as shown in FIG. 19B. Guard ring800 constitutes of a closed electrical-conductive ring. Ring 800 shortsthe magnetic field that passes through ring 800. When no magnetic fieldpasses through ring 800, or when the magnetic fields fade each other asin ring 800 between the electrified power transmission line segments 227i and 227 j, ring 800 is indifferent and/or has no significant influenceon the operation of power transmission line 20. Since the magnetic fieldcreated by extreme coils 27 i and 27 j are not faded, respective rings800 i and 800 j are active and capture the fields and reduce theresidual radiation. Other rings 800 have no significant magnetic fieldthrough them and thus, for example, remain indifferent. Rings 800 i and800 j slightly reduces the power provided by extreme coils 27 i and 27 jbut solve the residual radiation problem. Similar rings may beinstalled, in similar manner, in receiver array 10 or 117 (or 117 a).

In the remainder of this application, several specific non-limitingexemplary embodiments of the present invention are illustrated herein.

FIG. 20 is a schematic block diagram illustrating the two working modenature of the system according to some embodiments of the presentinvention. Configuration 2000A illustrates a power working mode wherepower grid input is provided into base station 2010 (the powertransmitter, on the road side) which in turn conveys the energy to theoperative segments along the power line 2030. Power receiver 2020 (onvehicle side) receives the electromagnetic flux which is then convertedto a direct current (DC) and provided to the load (motor). In acommunication working mode 2000B, same base station 2010 now acts acommunication receiver, while power receiver 2020 now acts ascommunication transmitter which transmits a request for power into powerline 2030 in a manner that same segments the are used on the power line(rode side) to carry out the power transmission are the same segmentsthat are used to receive communication signals form the vehicle side.Advantageously, the dual use of the segments on the road side enable amore efficient infrastructure.

FIG. 21 is a diagram illustrating some aspects relating to the coilsaccording to some embodiments of the present invention. As discussedabove, each segment includes two or more pairs of opposite-phase coils.Each coil can be of various shapes. The inventors have discovered thatapart from the circular spiral coil 2110, both ellipsoid spiral coil2120 and square spiral coil 2130 can be used efficiently. Coils in samesegment 2140 are connected in series, where each adjacent coils (e.g.,2140A and 2140B) have opposite phase. In a case of circular coils, it ispreferred to have two adjacent coils positioned at a radius R (of thecoil) apart from each other. From a mechanical aspect, a spectacle-likeshape 2150 may be used for each pair of the coils which may be fed by asingle wire 2170. In some embodiments, a bee-sting like connectors 2160Aand 2160B are on both sides of the segment for enable efficientconcatenation of segments and for preventing misalignment of segments.

FIG. 22 is a diagram illustrating other aspects relating to the coilsaccording to some embodiments of the present invention. To facilitatedeployment of the power line of segments, a roll 2210 of the segments2220 may be used. Using a flexible material is one way to ensure easydeployment of the powerline before asphalt is applied. In oneconfiguration, non-overlapping segment 2230A and 2230B can be used. Inanother embodiment, overlapping segment 2240A, 2240B and 2240C can beused. In overlapping segments, two adjacent coils are overlapping. Theelectromagnetic flux of overlapping coils are added in overlapping coilswhich assists in low k coupling coefficient level and when the receiveris closer to the edges of the segment.

FIG. 23 is a diagram illustrating yet other aspects relating to thecoils according to some embodiments of the present invention. A segment2310 on the power receiver (vehicle side) is shown in which the coilsare identical to those on the power transmitter (road side). A minimalnumber of two coils at the power receiving segment is contemplated. Inone non-limiting embodiment, 4 power receiver coils A, B, C, and D maybe 1.5R (R being radius of coils) apart where coils A, B, C, and D actas standalone inductor circuits which receive power independently ofeach other.

Alternatively, coil A and coil C may be connected in parallel and coilsB and coil D are also connected in parallel. Coils on power transmittersegment 2320 may be so arranged that power receiver coils A and Coverlap power transmitter coils 1 and 2 respectively and upon movementof power receiver (vehicle) to the right, power receiver coils B and Dbecome overlapping with power transmitter coils 2 and 4.

On the communication mode, communication transmitter segment 2330(vehicle side) has coils A and B (preferably different from powerreceiver coils A and B of 2310) that may not be transmittingsimultaneously but rather in a mutually exclusive manner (while Atransmits, B does not and vice versa). Communication receiver segment2340 (road side) uses the exact coils 1-4 of coils 1-4 of powertransmitter segment 2320 but additionally, a communication wire 2530B isadded to power wires 2350A and 2350B. In operation, the alternatingoperation (transmission) of communication signal over A and B of 2330guarantees a continuous current at communication wire 2350B which isinterpreted at the base station as a request for power from the vehicleat a specified segment.

FIG. 24 is a diagram illustrating aspects relating to the base stationaccording to some embodiments of the present invention. The base stationcontrols a plurality of segments independently of each other. An inputof a three phase power grid is fed into rectification a power factorcorrection (PFC) module 2420 which feeds direct current (DC) a inverter2430 which in turn generates an alternating current (AC) at a frequencyof approximately 85-90 KHz (being the preferred resonance frequency ofthe inductance circuits at the power transmitting and power receivingsegments) which is feeding the segments via respective switch cards2440A, 2440B, and 2440C, each switch card is associated with a differentsegment and controlled by a central controller 2410. In operation,whenever each switch card (e.g., 2440A) senses a request for power fromits respective segment (e.g., segment N, not shown), switch card (e.g.,2440A) notifies controller 2410 which in turn (after verifying identityand other network level considerations) instructs switch card (e.g.,2440A) to allow the 85-90 KHz power signal to reach the correspondingsegment (e.g., segment N).

FIG. 25 is a block diagram illustrating a non-limiting implementation ofthe switch card according to some embodiments of the present invention.The switch card may include a current loop 2550 encompassing orencircling the wire coming from the communication receiver coils on theroad side. When current is sensed by current sensor 2540, communicationreceiver interacts with the controller which determines whether, givenother parameters such as network availability and identification of thevehicle, to connect or disconnect switch 2520 via switch driver 2510.

FIG. 26 is a diagram illustrating aspects relating powering aspect onthe receiver side according to some embodiments of the presentinvention. Power transmitting coils 1 and 2 are instructed bycommunication module on the road side 2680 to provide energy torespective power receiving coils A, B, C, and D (resonance with 1 and 2only occur two at a time, A and C, and B and D). Each pair of coils A-Cand B-D is then fed into respective resonance capacitors 2620 and 2610respectively and then to impedance load matching capacitors 2630 and2640, to rectifiers 2660 and 2650 and eventually to voltage regulator2670 which outputs direct current to the load being the electric motorof the vehicle (not shown).

FIG. 27 is a circuit diagram illustrating other aspects relating to themechanism of the voltage regulator at the vehicle side (receiver)according to some embodiments of the present invention. Voltageregulating circuitry 2700 includes a receiver coil L1, a resonancecapacitor C1, an impedance load matching capacitor C2 for load R1.Capacitors C1 and C2 with coil L1 form together a current source, and assuch it may be short cut. It is referred herein as feed source. Sincethe feed source is a current source the output voltage is dependent uponthe values of the load resistor R1 and so in a case of a very hi load orin a case of a break, the output voltage will become thousands of voltswhich is destructive. During regulation, switch 1 (ON position)shortcuts the feed source via diode bridge D1, D2, D5, D6. When switch 1in in OFF position, a full rectifying of the feed source is carried outvia diode bridge D1, D2, D3, D4. VDC out control circuit samples theoutput voltage and when the voltage reaches the predefined value itswitches switch 1 to position ON, load R1 itself does not “see” a shortcut and so capacitor C1 maintains its voltage and discharges only viaR1. When voltage value decreases to a predefined value, switch 1 shiftsback to OFF and the process is repeated again and again. Regulating theoutput voltage will occur when switch 1 is an electronic switch such asIGBT or MOSFET that can handle the load and the required voltage. It isadvantageous to operate it via an insulated push circuit because of thevoltage difference between switch 1 and VDC OUT control.

FIG. 28 is a circuit diagram illustrating other aspects relating toprotecting against over voltage at the receiver (vehicle side) accordingto some embodiments of the present invention. This circuit connects inparallel to the circuit described in FIG. 27. Capacitor C9 is chargedvia resistor R21 when the output voltage reaches the voltage of Zenerdiode D8. When the voltage over capacitor C9 crosses the discharge pointof diode D7, a pulse is generated, and it will flow via the primarywindings of transformer X5 and will pass to its secondary windings.Transistor Q1 then will undergo breakdown and will shortcut switch 1.Therefore, the protection is applied when VD7+VD8 reaches an OverVoltage Protection value. This shortcut will be maintained until thecurrency via Q1 is halted in one of two possibilities: switch 2 in thecircuit shown in FIG. 25 is OFF or an initiated shortcut over transistorQ1.

Advantageously, this circuit is independent and does not require anexternal voltage source. Additionally, it is very reliable because ithas very few components, and all of them are passive except fromtransistor Q1.

FIG. 29 shows waveform diagrams 2900 illustrating aspects relating tothe power receiver (vehicle side) according to some embodiments of thepresent invention. In accordance with some embodiments of the presentinvention, it is possible to regulate the voltage at the receiver byrecognizing the phase of the current at the power transmitter segment.Waveform A is the inverter voltage (at the base station) while waveformsB, C, and D are the current phase at the power transmitter segment as“seen” by the load at the receiver (vehicle side). Phases B, C, and Dcan be easily detected by the current sensor as illustrated in FIG. 25discussed above.

In operation and as explained above, when switch 1 such as illustratedin FIG. 27 is shortcut, current sensor such as illustrated in FIG. 25detects a phase shift (waveform D herein) and disconnects in responsethe current flowing to the segment. Disconnecting the current releasestransistor Q1 (as in FIG. 28) and switches to communication receivingmode. In case there is incoming communication (e.g., the receiver islocated above the power transmit segments the there is demand on part ofthe receiver so there is a power request signal) then (and only then)switch 2 (as illustrated in FIG. 25) will shift into mode “ON”, thusallowing the voltage to rise again at the receiver. This process repeatsitself several time for regulating the voltage.

FIG. 30 is a circuit diagram illustrating other aspects relating to thecommunication mode at the receiver according to some embodiments of thepresent invention. Circuit 3000 includes voltage generator V1 whichgenerates the main frequency of ˜86 KHz for the resonance at the powertransmit segment. Switch 2 represents the main switch for activating thepower transmit segment. Coils L5 and L6 represent the two coils (inopposite phases) of the power transmit segment. Capacitors C13 and C17represent the resonance capacitors of the resonance frequency of thepower transmit segment. Coils L8 and L9 represent the communicationtransmit antennas (on the vehicle) on the communication frequency(hundreds of KHz). Capacitors C18 and C19 represent the resonancecapacitors of the transmitter (vehicle side) operating at thecommunication frequency. Capacitors C14 and C15 represent the resonancecapacitors of the communication receiver (road side) operating at thecommunication frequency. It is noted that while L4 and L5 serve as bothpower transmit antennas and communication receive antennas (for savingcost of copper along the power transmission line), it is preferred touse other coils (e.g., L8 and L9) as antennas for transmittingcommunication at the vehicle side from those used for power receipt atthe vehicle side.

In operation, v2 and v3 which operate the communication transmitter atthe vehicle side do not work simultaneously. The resonance current ofC14, C13 via coil L5 as well as resonance current of C14, C17 via coilL4 always flows via resistor R24. The alternating operation of coils L8and L9 guarantees an imbalance between the two coils on the segment (sothey will not cancel each other being in opposite phases). Thus, therewill always be a voltage drop over resistor R24 irrespective of thelocation of antennas L8 and L9, relative to coils L5 and L4 of the powertransmitter segment. In addition to the above, in a case that the switchis set to “ON”, there will be no communication in the circuit.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. It should be appreciated by persons skilled in the art thatmany modifications, variations, substitutions, changes, and equivalentsare possible in light of the above teaching. It is, therefore, to beunderstood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of theinvention.

1. A system comprising: a convertor configured to receive power from ageneral electricity network and to produce power of at least one phase;a primary inductive array for installation in a road configured tooperate as a primary winding to receive and inductively transfer powerfrom the convertor, the primary inductive array comprising a series ofsections, each section comprising at least a number of primary coilscorresponding to the number of phases of the convertor, wherein theprimary inductive array is in electromagnetic communication with areceiver array suitable for installation beneath a vehicle configured tooperate as a secondary winding, including at least one receiver sectioncomprising at least a number of receiver coils corresponding to thenumber of phases, each receiver coil being configured to receive powerfrom a corresponding primary coil installed in a road, while the vehiclemoves on the road above the primary coil, wherein said receiver array isconfigured to provide excess power back to the number of primary coils,said excess power being providable to other vehicles by the primaryinductive array; and a communications unit configured to receive asignal from a vehicle communications coil suitable for location in thevehicle in front of the receiver array in the driving direction of thevehicle, the communications coil configured to send a signal to acommunications unit via a corresponding one of the primary coils,wherein said signal is induced to the coils of the primary inductivearray and to operate corresponding primary inductive array sections toprovide power to a receiver attached to the vehicle.
 2. The system ofclaim 1, wherein each of the primary coils is configured to receivepower with a different phase shift.
 3. The system of claim 1, furthercomprising a number of groups of conductors corresponding to the numberof phases, each group carrying power with a different phase shift fromthe convertor to the primary inductive array.
 4. The system of claim 1,wherein said convertor comprises a switch configured to change the modeof operation of the convertor from full transmission mode to guidingsignaling mode when no receiver array is detected above the primarycoils, and vice versa when the receiver array is detected above theprimary coils.
 5. The system of claim 1, wherein the convertor isfurther configured to provide a guiding signal to be transmitted to thereceiver array at the vehicle via the primary inductive array.
 6. Thesystem of claim 1, wherein each of the receiver coils is configured toreceive power with a different phase shift from a corresponding primarycoil.
 7. The system of claim 1, further comprising at least two trackingcoils at two sides of the receiver array, positioned in equal distancesfrom the center of the receiver array, the at least two tracking coilsbeing configured to receive a guiding signal via a corresponding one ofthe primary coils, and to position the receiver array above the primarycoils according to average energy measured at the at least two trackingcoils.
 8. The system of claim 1, wherein said receiver array isconfigured to provide excess power back to the primary coils when thevehicle decreases its velocity.
 9. The system of claim 1, wherein saidvehicle further comprises a super capacitor configured to aggregatepower when the vehicle decreases its velocity.
 10. The system of claim1, wherein the inductance of each of the receiver coils is changeableseparately to conform to the resonance frequency of the primaryinductive army section by a regulation circuit, the regulation circuitcomprising a transformer to add inductance to the receiver coil andswitches to connect or disconnect inductors to change inductance valuesof the transformer.
 11. The system of claim 10, wherein the receiverarray comprises an accelerometer to detect vertical movements of thereceiver array in real time during travel and said two tracking coils todetect horizontal movements of the receiver array, wherein saidregulation circuit is configured to regulate the resonance frequency ofthe receiver coil when movements are detected.
 12. The system of claim1, wherein a receiver coil is configured to operate in resonance whilethe corresponding primary coil is configured to operate insub-resonance.
 13. The system of claim 1, wherein adjacent coils haveopposite current direction.
 14. A method using the system of claim 1,comprising: producing power of at least one phase by said convertor ofat least one phase; receiving the power from the convertor by saidprimary inductive array installed in a road; transmitting power, fromcorresponding coils of said primary inductive army installed in a roadand transmitting the power to the vehicle engine while the vehicle moveson the road above the primary coils, to said receiver array installedbeneath a vehicle; providing excess power back to the primary coils,said excess power being providable to other vehicles by the primacyinductive array; and receiving an identification signal at said primaryinductive array communications unit via a corresponding one of theprimary coils, from said vehicle communications coil located in front ofthe receiver array in the driving direction of the vehicle; receiving asignal at the communications unit included in said convertor from saidvehicle communications coil in a vehicle located above at least one ofthe primary inductive array sections; and operating correspondingprimary inductive array sections to provide power to said receiverattached to the vehicle.
 15. The method of claim 14, further comprisingdetecting in real time vertical and horizontal movements of the receiverarray, wherein said regulation circuit is configured to regulate theresonance frequency of the receiver coil when movements are detected.